SWRA825 January   2025 IWR6843 , LP87745-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Regulatory Needs for Electro-Sensitive Protective Equipment (ESPE)
    2. 1.2 Different Types of Electro-Sensitive Protective Equipment (ESPE)
  5. 2Advantages of Radar Sensors in Industrial Applications
  6. 3Safety Concept Evaluation/Analysis
    1. 3.1 System Requirements
      1. 3.1.1 Stationary Use Case
      2. 3.1.2 Mobile Use Case
    2. 3.2 Considerations for Sensing Architectures
      1. 3.2.1 System Level Architecture
        1. 3.2.1.1 Bi-Static With Spatial Diversity
        2. 3.2.1.2 Co-Located Bi-Static (Two Sensor Products)
        3. 3.2.1.3 Co-Located Bi-Static (Single Sensor Product, Dual IWR6843)
        4. 3.2.1.4 Mono-Static (Single Sensor Product, Single IWR6843)
        5. 3.2.1.5 Summary
      2. 3.2.2 Latent Fault Monitoring
    3. 3.3 Sensor Level Architecture
      1. 3.3.1 Sensor Level Architecture for CAT 2
      2. 3.3.2 Sensor Level Architecture for Cat 3
  7. 4IEC TS 61496-5 Functional Test Results
  8. 5Other Considerations
    1. 5.1 Vibrations
    2. 5.2 Clock
  9. 6Conclusion
  10. 7References

3.1.1 Stationary Use Case

The operation of industrial robots often involves risks due to high speeds, heavy loads, and sharp tools. Ensuring the safety of human operators in proximity to these robots is paramount. IEC 61496, the international standard governing the design and application of electro-sensitive protective equipment (ESPE), provides a framework for implementing safety measures using devices such as safety sensors.

A radar sensor is ideal for detecting entry into a hazardous area, offering adjustable protection zones. The radar sensor would be positioned in a way to cover the robot's operating area, ensuring all potential entry points are monitored. Different zones could be defined as seen in Figure 3-5.

If a person enters the yellow warning zone, the system reduces the robot's speed, allowing for continued operation while signaling caution. If a person breaches the red hazard zone, the system initiates an emergency stop of the robot to prevent harm within a specified safety time.

Industrial Robot (Safer Human Presence Detection) Figure 3-5 Industrial Robot (Safer Human Presence Detection)

Safety assessments are a critical step in designing industrial robot applications, particularly in fenceless setups where human workers share close proximity with robots. A very simplified example of safety assessment and calculation follows. For this specific example, consider the case of an industrial robot and carry a risk assessment based on a typical robot arm, speed, stopping time in relation to typical human worker speed to provide background for the considered safety time.

Key Definitions

  • Stop Zone:

    The area where the robot could strike a human if its arm reaches the furthest extent of its motion.

    UR10 Robot Arm Reach: 1.0m

    -> Stop Zone: 1.0m

  • Slow Down Zone:

    The area where the robot must slow down to prevent a human, moving at maximum speed, from entering the stop zone during the robot's stopping time.

    Maximum Human Speed: 3.6m/s (13 km/h)

    Worst-Case Stopping Time: 1250 ms (1.25 seconds)

    Slow down zone has to be bigger than 3.6m/s * 1250ms + 1m = 5.5m

    -> Target Slow Down Zone: 6.0 m (rounded up for margin).

  • Safety Time Calculation

    The safety time is the margin required to account for system reaction delays.

    Safety time ~(target slow down zone- min slow down zone)/max human speed

    0.5m/3.6m/s =138.9ms

    To provide additional safety margins, the safety time is rounded to 100ms which seems to be a realistic value.

    This simplified safety assessment highlights the importance of understanding both robot capabilities and human factors in defining critical safety parameters. In this example, the key outcomes are:

  • Stop Zone: 1.0m
  • Target Slow Down Zone:

    6.0m

  • Safety Time:

    100ms